1. Field of the Invention
The present invention relates to an image forming apparatus and, more particularly, relates to an image forming apparatus in which a sheet conveying path on which a sheet passes is provided above a sheet storage portion attached to an apparatus body.
2. Description of the Related Art
Conventionally, there are image forming apparatuses which form images on a sheet using an electrophotograhic image forming system, and these image forming apparatuses include, for example, copying machines, laser beam printers, LED printers, facsimile apparatuses and word processors. Generally, in such a conventional image forming apparatus, standard size sheets of a high use frequency are stacked in a sheet feeding cassette in which a predetermined number of sheets can be stacked and are fed, and special sheets other than standard size sheets of a low use frequency such as cardboards and standard size sheets such as elongated sheets are manually fed.
Further, to feed a cardboard and a special sheet, one or a plurality of sheets is manually set in a manual feed tray, and is fed toward an image forming portion by a guiding portion of a sheet conveying path. Meanwhile, in such an image forming apparatus, the guiding portion of the sheet conveying path is arranged above the sheet feeding cassette.
Further, some conventional image forming apparatuses have re-feeding/conveying portion which feeds again a sheet for forming an image on a back surface after an image is formed on one surface, to an image forming portion. Furthermore, also in the re-feeding/conveying portion of such an image forming apparatus, a guiding portion which guides to the image forming portion a sheet on one surface of which an image is formed is arranged above the sheet feeding cassette (see Japanese Patent Laid-Open No. 2006-69732).
Incidentally, in such a conventional image forming apparatus, a gap is provided between a guiding portion and a sheet feeding cassette such that, when the sheet feeding cassette is attached and detached to and from the image forming apparatus body, the guiding portion of the sheet conveying path and the sheet feeding cassette do not interfere with each other.
Meanwhile, a plurality of conveying rollers which forms pairs of conveying rollers is attached to the guiding portion, and therefore a reaction force is applied from the conveying rollers when a sheet is conveyed. Further, when the reaction force of the conveying rollers is applied in this way, the gap is formed between the conveying rollers and the sheet feeding cassette, and therefore there is a concern that the conveyance guiding portion deflects downward and deforms. Furthermore, even when, for example, an image forming apparatus is left in high-temperature environment after product shipping, a gap is formed between a sheet feeding cassette and a conveyance guiding portion, and therefore there is a concern that the conveyance guiding portion deflects downward and deforms.
Meanwhile, when the feeding guiding portion deforms downward in this way, for example, a sheet nipping pressure of pairs of conveying rollers decreases and a conveying force decreases. In addition, to prevent deformation of the conveyance guiding portion, there is a countermeasure of sufficiently securing the thickness of the conveyance guiding portion and improving rigidity of the conveyance guiding portion or reinforcing the conveyance guiding portion using, for example, a sheet metal.
However, when the thickness of the conveyance guiding portion is sufficiently secured or the conveyance guiding portion is reinforced using, for example, a metal sheet, the image forming apparatus not only becomes heavy and large but also causes an increase in cost. That is, the above countermeasure cannot sufficiently meet requests of reducing cost, reducing the weight and reducing the size of the image forming apparatus.
The present invention is made in light of this situation, and it is desirable to provide an image forming apparatus which is low-cost, small and light, and which can stably convey a sheet.